Various methods of manufacturing bipolar transistors of various types and MOS transistors of various types are known. Such methods are generally provided to decrease the number of manufacturing steps and to optimize each of the transistors.
A method minimizing the number of manufacturing steps and optimizing the performance of PNP-type and NPN-type bipolar transistors is needed. The desired performances of the PNP bipolar transistor are, for example, a gain higher than 100 and a transition frequency greater than 25 GHz. The desired performances of the NPN-type bipolar transistor are, for example, a cut-off frequency greater than 300 GHz.